The copper, silver, and gold complex dielectric functions are empirical values by Johnson and Christy [1]} obtained by reflection and transmission spectroscopy on vacuum-evaporated films at room temperature. Film-thickness in the Johnson and Christy study ranged from \(185\,\) Å– \(500\,\) Å. Dielectric functions in the film-thickness range \(250\,\) Å – \(500\,\) Å did not vary significantly. In our work, the intermediate value \(340\,\) Å was chosen to represent bulk mode dominant (yet still nanoscale) metallic thin films.
